Search

To optimize the farming strategy of economically important seaweeds, we grew Gracilaria lemaneiformis at different seawater depths under natural solar radiation with or without UV irradiances. Our results showed that solar UV radiation (UVR, 295–395 nm) significantly inhibited its growth and photosynthesis in the surface seawater; however, such a negative effects became inverse at 1.7 m with levels of UVR being about 11.7 W m− 2. The maximal growth rates were found at 1.7, 0.8 m when the thalli grown at PAR + UVR or PAR only conditions, respectively. UV-absorbing compounds in the algal thalli were up to 85% higher under PAR + UVR compared to PAR alone treatment and they increased with decreased depths even in the absence of UVR. The enhanced growth rate in the presence of UVR could be attributed to enhanced photosynthesis under moderate levels of solar radiation by UV-A. Our study clearly showed that UV-induced growth inhibition could be minimized or avoided by optimizing the alga's farming depth in different waters of different transparency, so that Gracilaria's biomass production could be increased.

Rural to urban migration under China’s rapid urbanization has created inefficient use of rural homestead land. To address these issues, there is increasing interest in rural homestead system reform in China. Although several reforms have been implemented in pilot areas, reviews of the related accumulated literature are rare. The objectives of this study are the following: (i) to discuss the research transition from the “separation of two rights” to the “separation of three rights” in homestead management and (ii) draw conclusions on current research conditions, hot topics, and trends. This study provides a reference for further and deeper rural homestead system reform in China and regions worldwide. We collected and sorted 640 research papers on the topic of the separation of three rights in homestead (hereinafter referred to as STRH) or the homestead land use rights from China National Knowledge Infrastructure (CNKI) and used CiteSpace and VOSviewer to visualize and map knowledge domains. The results show that: (1) From the study of the homestead land use rights to the study of the STRH, there is pronounced synergy between national policies and the number of published papers. The STRH has become a popular research field since 2018. (2) Most researchers are experts and scholars engaged in the study of agricultural economics, civil and commercial law, administrative law, or local legal systems. (3) Current and future studies on the STRH are and will be conducted in terms of the definition of concepts and connotations, confirmation of rights and registration, implementation paths, rural homestead system reform, rural revitalization strategy, reform challenges and countermeasures, risk control, and overall planning. (4) The studies on the STRH have integrity, and show characteristics of inheritance between it and studies on the homestead land use rights. (5) Studies on typical cases for the STRH should be conducted in combination with the latest strategic requirements such as rural land system reform, rural revitalization strategy, and integrated urban and rural development.

Red tide and green tide are two common algal blooms that frequently occur in many areas in the global oceans. The algae causing red tide and green tide often interact with each other in costal ecosystems. However, little is known on how future CO2-induced ocean acidification combined with temperature variation would affect the interaction of red and green tides. In this study, we cultured the red tide alga Skeletonema costatum and the green tide alga Ulva linza under ambient (400 ppm) and future CO2 (1000 ppm) levels and three temperatures (12, 18, 24 °C) in both monoculture and coculture systems. Coculture did not affect the growth rate of U. linza but significantly decreased it for S. costatum. Elevated CO2 relieved the inhibitory effect of U. linza on the growth of S. costatum, particularly for higher temperatures. At elevated CO2, higher temperature increased the growth rate of S. costatum but reduced it for U. linza. Coculture with U. linza reduced the net photosynthetic rate of S. costatum, which was relieved by elevated CO2. This pattern was also found in Chl a content, indicating that U. linza may inhibit growth of S. costatum via harming pigment synthesis and thus photosynthesis. In monoculture, higher temperature did not affect respiration rate of S. costatum but increased it in U. linza. Coculture did not affect respiration of U. linza but stimulated it for S. costatum, which was a signal of responding to biotic and/abiotic stress. The increased growth of S. costatum at higher temperature and decreased inhibition of U. linza on S. costatum at elevated CO2 suggest that red tides may have more advantages over green tides in future warmer and CO2-enriched oceans.